From 14e0e825b2c01247e610666087328e6fbd4c785c Mon Sep 17 00:00:00 2001
From: Victor Lin <13424970+victorlin@users.noreply.github.com>
Date: Wed, 13 Nov 2024 15:56:08 -0800
Subject: [PATCH] _setDisplayName: Replace optional chaining with proper error
 handing

With the current code, it is not possible for resources[i-1] to be
undefined. Make this clear with type narrowing.
---
 static-site/src/components/ListResources/ResourceGroup.tsx | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/static-site/src/components/ListResources/ResourceGroup.tsx b/static-site/src/components/ListResources/ResourceGroup.tsx
index 079e86536..5a9345aba 100644
--- a/static-site/src/components/ListResources/ResourceGroup.tsx
+++ b/static-site/src/components/ListResources/ResourceGroup.tsx
@@ -265,7 +265,11 @@ function _setDisplayName(resources: Resource[]): DisplayNamedResource[] {
     if (i===0) {
       name = r.nameParts.join(sep);
     } else {
-      let matchIdx = r.nameParts.map((word, j) => word === resources[i-1]?.nameParts[j]).findIndex((v) => !v);
+      const previousResource = resources[i-1];
+      if (previousResource === undefined) {
+        throw new InternalError("Previous resource is undefined. Check that this is not run on i===0.");
+      }
+      let matchIdx = r.nameParts.map((word, j) => word === previousResource.nameParts[j]).findIndex((v) => !v);
       if (matchIdx===-1) { // -1 means every word is in the preceding name, but we should display the last word anyway
         matchIdx = r.nameParts.length-2;
       }